Problems from Computation of images and inverse images

Consider the function $$f$$ defined by three plus the root of a given real number. Find its analytical expression as well as $$f (1), f (4)$$ and $$f^{-1}(7)$$.

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We write the algebraic expression of the function:


We can calculate now: $$$f(1)=\sqrt{1}+3=1+3=4$$$ $$$f(4)=\sqrt{4}+3=2+3=5$$$ $$$f^{-1}(7):$$$ $$$7=\sqrt{x}+3$$$ $$$4=\sqrt{x}$$$ $$$x=16$$$






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